JP6964520B2 - Cleaning method for SiC single crystal growth furnace - Google Patents

Cleaning method for SiC single crystal growth furnace Download PDF

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JP6964520B2
JP6964520B2 JP2017559181A JP2017559181A JP6964520B2 JP 6964520 B2 JP6964520 B2 JP 6964520B2 JP 2017559181 A JP2017559181 A JP 2017559181A JP 2017559181 A JP2017559181 A JP 2017559181A JP 6964520 B2 JP6964520 B2 JP 6964520B2
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陽祐 谷本
秀行 栗原
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Showa Denko KK
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/02—Pretreatment of the material to be coated
    • C23C16/0227—Pretreatment of the material to be coated by cleaning or etching
    • C23C16/0245—Pretreatment of the material to be coated by cleaning or etching by etching with a plasma
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
    • C23C16/4405—Cleaning of reactor or parts inside the reactor by using reactive gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B5/00—Cleaning by methods involving the use of air flow or gas flow
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B08—CLEANING
    • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
    • B08B9/00—Cleaning hollow articles by methods or apparatus specially adapted thereto 
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/02—Pretreatment of the material to be coated
    • C23C14/021—Cleaning or etching treatments
    • C23C14/022—Cleaning or etching treatments by means of bombardment with energetic particles or radiation
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/56—Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks
    • C23C14/564—Means for minimising impurities in the coating chamber such as dust, moisture, residual gases
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
    • C30B29/10—Inorganic compounds or compositions
    • C30B29/36—Carbides
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Mechanical Engineering (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • General Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
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  • Crystals, And After-Treatments Of Crystals (AREA)
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Description

本発明は、ＳｉＣ単結晶成長炉のクリーニング方法に関する。
本願は、２０１５年１２月２８日に、日本に出願された特願２０１５−２５６２８７号に基づき優先権を主張し、その内容をここに援用する。The present invention relates to a method for cleaning a SiC single crystal growth furnace.
The present application claims priority based on Japanese Patent Application No. 2015-256287 filed in Japan on December 28, 2015, the contents of which are incorporated herein by reference.

炭化珪素（ＳｉＣ）は、重要なセラミックス材料として多方面で使用されている。近年、炭化珪素のエピタキシャル成長技術が注目されており、特にその絶縁破壊電圧の高さや高温作動時における信頼性から、低消費電力のトランジスタなど用途が開発されている。
このような用途に用いられる炭化珪素としては、高純度な単結晶のバルクあるいは膜（薄膜、厚膜いずれも含む）である必要がある。Silicon carbide (SiC) is widely used as an important ceramic material. In recent years, the epitaxial growth technology of silicon carbide has attracted attention, and in particular, applications such as low power consumption transistors have been developed because of its high dielectric breakdown voltage and reliability during high-temperature operation.
The silicon carbide used for such applications needs to be a bulk or film (including both a thin film and a thick film) of a high-purity single crystal.

炭化珪素の単結晶膜を成膜する方法としては、化学気相堆積法（Ｃｈｅｍｉｃａｌ Ｖａｐｏｒ Ｄｅｐｏｓｉｔｉｏｎ法；ＣＶＤ法）を用いて、Ｃ含有ガス（プロパンガスなど）とＳｉ含有ガス（シランガスなど）との化学反応により炭化珪素の単結晶膜を成長させる方法や、モノメチルシランをＣＶＤ法の原料として炭化珪素の単結晶膜を成長させる方法が知られている。 As a method for forming a single crystal film of silicon carbide, a chemical vapor deposition method (CVD method) is used to combine a C-containing gas (propane gas or the like) and a Si-containing gas (silane gas or the like). A method of growing a silicon carbide single crystal film by a chemical reaction and a method of growing a silicon carbide single crystal film using monomethylsilane as a raw material for a CVD method are known.

これらのＣＶＤ法を用いて高純度な炭化珪素単結晶膜を作製するには、炭化珪素成膜時に、１５００℃以上の高い温度が必要である。そのため、ＳｉＣ単結晶成長炉（以下、単に「成長炉」ということがある）の内壁やウエハを設置するサセプタなどの成長炉内の部材（以下、成長炉の内壁及び部材を合わせて「炉内基材」ということがある）には、高耐熱性の材料が用いられ、主としてカーボン母材の表面にＣＶＤ法によって緻密な多結晶のＳｉＣを被覆したもの（ＳｉＣコート）が用いられる。
ここで、ＳｉＣ単結晶成長炉とは、ＳｉＣ単結晶膜やＳｉＣ単結晶インゴットなどのＳｉＣ単結晶を成長させるために用いられる炉（容器、チャンバ）を全て含む。In order to produce a high-purity silicon carbide single crystal film using these CVD methods, a high temperature of 1500 ° C. or higher is required at the time of film formation of silicon carbide. Therefore, the inner wall of the SiC single crystal growth furnace (hereinafter, may be simply referred to as “growth furnace”) and the members inside the growth furnace such as the susceptor on which the wafer is installed (hereinafter, the inner wall and members of the growth furnace are collectively referred to as “inside the furnace”. A material having high heat resistance is used as the base material), and a material in which the surface of the carbon base material is coated with dense polycrystalline SiC by the CVD method (SiC coating) is mainly used.
Here, the SiC single crystal growth furnace includes all furnaces (containers, chambers) used for growing a SiC single crystal such as a SiC single crystal film and a SiC single crystal ingot.

また、ＣＶＤ法による膜成長の際に、成長炉の内壁やサセプタなどの炉内基材にも炭化珪素が付着し、堆積してしまう。それらの基材に堆積した炭化珪素の堆積物（以下、「ＳｉＣ堆積物」という）は、剥離、脱落して、炭化珪素薄膜の成長表面に落下付着し、結晶成長を阻害したり、欠陥を生じさせたりする原因となる。そのため、定期的に成長炉の内壁などに堆積したＳｉＣ堆積物を取り除かなければならない。その除去方法として、従来、炭化珪素が成長炉の内壁に堆積した場合には、工具を用いて剥離除去するか、容器を定期的に交換する方法が採用されていた。 Further, when the film is grown by the CVD method, silicon carbide adheres to and accumulates on the inner wall of the growth furnace and the base material in the furnace such as the susceptor. The silicon carbide deposits (hereinafter referred to as "SiC deposits") deposited on these substrates peel off and fall off, and fall and adhere to the growth surface of the silicon carbide thin film, inhibiting crystal growth and causing defects. It may cause it to occur. Therefore, the SiC deposits deposited on the inner wall of the growth furnace must be removed on a regular basis. As a method for removing the silicon carbide, when silicon carbide is deposited on the inner wall of the growth furnace, it has been peeled off with a tool or the container has been replaced regularly.

堆積した炭化珪素の削り取りや成長炉の交換には極めて長い作業時間を要し、反応器を長期間にわたり大気開放する必要があることから、歩留まりの悪化など生産性にも影響を与える原因となっていた。そのため、無機物質を効率よく除去するガスを用いて、成長炉の内壁などに付着した炭化珪素を化学的に除去するクリーニング方法が検討されている。 It takes an extremely long working time to scrape off the accumulated silicon carbide and replace the growth furnace, and it is necessary to open the reactor to the atmosphere for a long period of time, which causes a deterioration in yield and other factors that affect productivity. Was there. Therefore, a cleaning method for chemically removing silicon carbide adhering to the inner wall of a growth furnace or the like by using a gas that efficiently removes inorganic substances has been studied.

特許文献１には、炭化珪素成膜装置の成膜チャンバ内で使用するサセプタの材質をバルクの炭化珪素のみとすることで、サセプタに堆積した炭化珪素の堆積物をプラズマ化させたフッ素と酸素でのエッチングにより除去した後にサセプタを再利用できる方法が開示されている。 In Patent Document 1, by using only bulk silicon carbide as the material of the susceptor used in the film forming chamber of the silicon carbide film forming apparatus, fluorine and oxygen obtained by plasma-forming the silicon carbide deposits deposited on the susceptor. A method is disclosed in which the susceptor can be reused after being removed by etching in.

特許文献２には、予めプラズマ化された三フッ化窒素等のフッ素含有ガスにより炭化珪素よりなる堆積物を除去し、その排ガスを分析することで処理時間を調整する方法が開示されている。 Patent Document 2 discloses a method of adjusting the treatment time by removing deposits made of silicon carbide with a fluorine-containing gas such as nitrogen trifluoride that has been plasmatized in advance and analyzing the exhaust gas thereof.

炭化珪素の単結晶を種結晶上に成長させて単結晶インゴットを製造する方法としては、昇華再結晶法（改良レリー法）が知られている（例えば、特許文献３参照）。この昇華再結晶法ではＳｉＣ単結晶成長炉内で、昇華用原料を２０００℃以上に加熱することで、原料を昇華させて昇華ガスを発生させ、その昇華ガスを原料収容部よりも数１０〜数１００℃低温にした種結晶へ供給することにより、この種結晶上に単結晶を成長させる方法である。
この方法においても、成長炉の内壁などの炉内基材に炭化珪素が付着し、堆積してしまう点は、炭化珪素の単結晶膜を成膜する場合と同様であり、堆積したＳｉＣ堆積物を除去したり、部材を交換したりしている。A sublimation recrystallization method (improved release method) is known as a method for producing a single crystal ingot by growing a single crystal of silicon carbide on a seed crystal (see, for example, Patent Document 3). In this sublimation recrystallization method, the raw material for sublimation is heated to 2000 ° C. or higher in the SiC single crystal growth furnace to sublimate the raw material to generate sublimation gas, and the sublimation gas is generated by several 10 to 10 from the raw material accommodating portion. This is a method of growing a single crystal on a seed crystal by supplying the seed crystal to a temperature of several hundred degrees Celsius.
In this method as well, the point that silicon carbide adheres to and deposits on the inner wall of the growth furnace and the like is the same as in the case of forming a single crystal film of silicon carbide, and the deposited SiC deposits. Is being removed or parts are being replaced.

特開２０１５−５３３９３号公報Japanese Unexamined Patent Publication No. 2015-53393 特開２０１３−２５１４８７号公報Japanese Unexamined Patent Publication No. 2013-251487 特開２００４−２２４６６３号公報Japanese Unexamined Patent Publication No. 2004-224663

しかしながら、特許文献１には、エッチングにより炭化珪素の堆積物だけでなくサセプタ自身もエッチングされ得ることが記載されている。また、特許文献１には、サセプタにバルクの炭化珪素を用いることで平均表面粗さＲａを小さくすることが可能となり、サセプタのエッチング速度を小さくできることが記載されている。しかし、炭化珪素のエピタキシャル成長炉のうちの反応ガスが接する部分や部材全てをバルクの炭化珪素だけで構成することは極めて困難であり、インサイチュウ（ｉｎ−ｓｉｔｕ）への展開は困難である。 However, Patent Document 1 describes that not only the silicon carbide deposit but also the susceptor itself can be etched by etching. Further, Patent Document 1 describes that by using bulk silicon carbide for the susceptor, the average surface roughness Ra can be reduced and the etching rate of the susceptor can be reduced. However, it is extremely difficult to construct all the parts and members of the epitaxial growth furnace of silicon carbide that come into contact with the reaction gas only with bulk silicon carbide, and it is difficult to deploy them in situ.

また、特許文献２は、炭化珪素よりなる付着物と、カーボン母材の表面にＣＶＤ法によって緻密な多結晶を被覆したもの（ＳｉＣコート）との僅かな反応性の差を排ガスの分析により認識し、制御しようとする発明であるが、炉内基材へのダメージを防ぐことは困難であった。 Further, Patent Document 2 recognizes a slight difference in reactivity between a deposit made of silicon carbide and a carbon base material coated with dense polycrystals by a CVD method (SiC coat) by analysis of exhaust gas. However, although it is an invention to be controlled, it is difficult to prevent damage to the substrate in the furnace.

以上のように、ＳｉＣ単結晶成長炉において、炉内基材のＳｉＣコートを傷めることなく余分なＳｉＣ堆積物を選択的に除去する方法を見出すために多くの試行錯誤が行われてきた。 As described above, in the SiC single crystal growth furnace, many trials and errors have been carried out in order to find a method for selectively removing excess SiC deposits without damaging the SiC coat of the base material in the furnace.

本発明は、上記の課題に鑑みてなされたものであり、炉内基材を構成するＳｉＣコートあるいはＳｉＣバルクへの損傷を抑制して、ＳｉＣ堆積物を選択的に除去することができるＳｉＣ単結晶成長炉のクリーニング方法を提供することを目的とする。 The present invention has been made in view of the above problems, and is capable of selectively removing SiC deposits by suppressing damage to the SiC coat or SiC bulk constituting the base material in the furnace. It is an object of the present invention to provide a cleaning method for a crystal growth furnace.

本発明は、上記課題を解決するために、以下の手段を採用した。 The present invention employs the following means in order to solve the above problems.

（１）少なくとも表面が粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５%以上、１００%以下である３Ｃ−ＳｉＣ多結晶からなる炉内基材を備えたＳｉＣ単結晶成長炉を、ガスを用いてクリーニングする方法であって、フッ素ガスと不活性ガスおよび空気の少なくとも一方との混合ガスを、ノンプラズマ状態で前記ＳｉＣ単結晶成長炉内に流通させて、該ＳｉＣ単結晶成長炉内に堆積したＳｉＣ堆積物を選択的に除去するものであり、前記混合ガスは１体積％以上、２０体積％以下のフッ素ガスと８０体積％以上、９９体積％以下の不活性ガスとからなり、ＳｉＣ単結晶成長炉内温度が２００℃以上、５００℃以下であることを特徴とするＳｉＣ単結晶成長炉のクリーニング方法。
（２）前記不活性ガスが、窒素ガス、アルゴンガス、及びヘリウムガスからなる群から選択されたものであることを特徴とする（１）に記載のＳｉＣ単結晶成長炉のクリーニング方法。
（３）前記不活性ガスが窒素ガスまたはアルゴンガスのいずれかであることを特徴とする（２）に記載のＳｉＣ単結晶成長炉のクリーニング方法。(1) A SiC single crystal having an in-core substrate composed of 3C-SiC polycrystals having at least a surface having a strength ratio of the (111) plane to another crystal plane of 85% or more and 100% or less in powder XRD analysis. A method of cleaning a growth furnace with a gas, in which a mixed gas of fluorine gas, an inert gas, and at least one of air is circulated in the SiC single crystal growth furnace in a non-plasma state, and the SiC is used. The SiC deposits deposited in the single crystal growth furnace are selectively removed, and the mixed gas is 1% by volume or more and 20% by volume or less of fluorine gas and 80% by volume or more and 99% by volume or less of inert gas. A method for cleaning a SiC single crystal growth furnace, which comprises gas and has a SiC single crystal growth furnace having a temperature of 200 ° C. or higher and 500 ° C. or lower.
(2) The method for cleaning a SiC single crystal growth furnace according to (1), wherein the inert gas is selected from the group consisting of nitrogen gas, argon gas, and helium gas.
(3) The method for cleaning a SiC single crystal growth furnace according to (2), wherein the inert gas is either nitrogen gas or argon gas.

本発明のＳｉＣ単結晶成長炉のクリーニング方法によれば、炉内基材を構成するＳｉＣコートあるいはＳｉＣバルクへの損傷を抑制して、ＳｉＣ堆積物を選択的に除去することができるＳｉＣ単結晶成長炉のクリーニング方法を提供することができる。 According to the cleaning method of the SiC single crystal growth furnace of the present invention, the SiC single crystal capable of selectively removing the SiC deposit by suppressing damage to the SiC coat or the SiC bulk constituting the base material in the furnace. A method of cleaning the growth furnace can be provided.

クリーニング試験で使用した反応炉の断面模式図である。It is sectional drawing of the reaction furnace used in the cleaning test. クリーニング試験で用いたサンプルの断面ＳＥＭ像であり、下段は対照サンプルのＳＥＭ像、上段は評価用サンプルのＳＥＭ像であり、（Ａ）はクリーニング試験前のものであり、（Ｂ）は実施例１のクリーニング試験後のものであり、（Ｃ）は実施例２のクリーニング試験後のものである。The cross-sectional SEM image of the sample used in the cleaning test, the lower row is the SEM image of the control sample, the upper row is the SEM image of the evaluation sample, (A) is the one before the cleaning test, and (B) is the example. 1 is after the cleaning test, and (C) is after the cleaning test of Example 2.

以下、本発明を適用したＳｉＣ単結晶成長炉のクリーニング方法について、図面を用いてその構成を説明する。なお、以下の説明で用いる図面は、特徴をわかりやすくするために便宜上特徴となる部分を拡大して示している場合があり、各構成要素の寸法比率などは実際と同じであるとは限らない。また、以下の説明において例示される材料、寸法等は一例であって、本発明はそれらに限定されるものではなく、発明の効果を奏する範囲で適宜変更して実施することが可能である。 Hereinafter, the configuration of a cleaning method for a SiC single crystal growth furnace to which the present invention is applied will be described with reference to the drawings. In the drawings used in the following description, the featured parts may be enlarged for convenience in order to make the features easier to understand, and the dimensional ratios of each component may not be the same as the actual ones. .. Further, the materials, dimensions, etc. exemplified in the following description are examples, and the present invention is not limited thereto, and can be appropriately modified and carried out within the range in which the effects of the invention are exhibited.

本発明の一実施形態に係るＳｉＣ単結晶成長炉のクリーニング方法は、少なくとも表面が粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５%以上、１００%以下である３Ｃ−ＳｉＣ多結晶からなる炉内基材を備えたＳｉＣ単結晶成長炉を、ガスを用いてクリーニングする方法であって、フッ素ガスと不活性ガスおよび空気の少なくとも一方との混合ガスを、ノンプラズマ状態でＳｉＣ単結晶成長炉内に流通させて、ＳｉＣ単結晶成長炉内に堆積したＳｉＣ堆積物を選択的に除去する。 In the method for cleaning a SiC single crystal growth furnace according to an embodiment of the present invention, the intensity ratio of the (111) plane to another crystal plane in powder XRD analysis is at least 85% or more and 100% or less. A method of cleaning a SiC single crystal growth furnace provided with an in-core substrate made of SiC polycrystals using a gas, in which a mixed gas of fluorine gas, an inert gas, and at least one of air is put into a non-plasma state. The SiC single crystal growth furnace is circulated to selectively remove the SiC deposits deposited in the SiC single crystal growth furnace.

ここで、「ＳｉＣ単結晶成長炉」としては上述したように、ＳｉＣ単結晶の成長を行う炉であれば制限なく含み、例えば、ＳｉＣエピタキシャル膜を含むＳｉＣ単結晶膜の成膜装置やＳｉＣ単結晶（インゴット）製造装置などが備える炉（容器、チャンバ）が挙げられる。ＳｉＣ単結晶膜の成膜装置としては、通常、高周波電源を用いてサセプタを１４００〜１６００℃程度に誘導加熱させ、そのサセプタ上にＳｉＣ基板を設置して原料ガスを導入する方法が用いられる。
また、「炉内基材」は上述のとおり、ＳｉＣ単結晶成長炉の内壁およびＳｉＣ単結晶成長炉内の部材を含む。本発明のクリーニング方法の適用対象となる炉内基材の一例としては、少なくとも一部がカーボン母材からなり、そのカーボン母材の表面を炭化珪素の保護膜で被覆した１５００℃以上の高温条件に耐えうる基材が挙げられる。
また、「少なくとも表面が粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５%以上、１００%以下である３Ｃ−ＳｉＣ多結晶からなる炉内基材」とは、粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５%以上、１００%以下である３Ｃ−ＳｉＣ多結晶によって表面が被覆された炉内基材（すなわち、その３Ｃ−ＳｉＣ多結晶とは異なる材料からなる部分を有する炉内基材）、及び、粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５%〜１００%である３Ｃ−ＳｉＣ多結晶からなる炉内基材の両方を含む。前者は３Ｃ−ＳｉＣ多結晶コートを有する炉内基材であり、後者は３Ｃ−ＳｉＣ多結晶バルクでなる炉内基材である。
また、「ノンプラズマ状態」は、プラズマになっていない状態を指す。
また、「ＳｉＣ単結晶成長炉内に堆積したＳｉＣ堆積物」は、ＳｉＣ単結晶成長炉の内壁やＳｉＣ単結晶成長炉内の部材に堆積したＳｉＣ堆積物である。従って、「少なくとも表面が粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５%以上、１００%以下である３Ｃ−ＳｉＣ多結晶からなる炉内基材」上に堆積したＳｉＣ堆積物だけでなく、それ以外の炉内基材上に堆積したＳｉＣ堆積物も含む。Here, as described above, the "SiC single crystal growth furnace" includes, as long as it is a furnace for growing a SiC single crystal, without limitation. Examples thereof include furnaces (containers, chambers) provided in crystal (ingot) manufacturing equipment and the like. As a film forming apparatus for a SiC single crystal film, a method is usually used in which a susceptor is induced and heated to about 1400 to 1600 ° C. using a high-frequency power source, and a SiC substrate is placed on the susceptor to introduce a raw material gas.
Further, as described above, the "base material in the furnace" includes the inner wall of the SiC single crystal growth furnace and the members in the SiC single crystal growth furnace. As an example of the base material in the furnace to which the cleaning method of the present invention is applied, a high temperature condition of 1500 ° C. or higher in which at least a part is made of a carbon base material and the surface of the carbon base material is coated with a protective film of silicon carbide. A base material that can withstand the above can be mentioned.
Further, "a base material in a furnace composed of 3C-SiC polycrystals having at least a surface having a strength ratio of the (111) plane to another crystal plane in powder XRD analysis of 85% or more and 100% or less" is defined as powder XRD. With the in-core substrate (ie, its 3C-SiC polycrystal) whose surface is coated with a 3C-SiC polycrystal having an intensity ratio of the (111) plane to the other crystal plane in the analysis of 85% or more and 100% or less. Is an in-core substrate having parts made of different materials) and in-furnace consisting of 3C-SiC polycrystals in which the strength ratio of the (111) plane to the other crystal planes in the powder XRD analysis is 85% to 100%. Includes both substrates. The former is an in-core base material having a 3C-SiC polycrystalline coat, and the latter is an in-core base material made of 3C-SiC polycrystalline bulk.
Further, the "non-plasma state" refers to a state in which the plasma is not generated.
Further, the "SiC deposit deposited in the SiC single crystal growth furnace" is a SiC deposit deposited on the inner wall of the SiC single crystal growth furnace and the members in the SiC single crystal growth furnace. Therefore, SiC deposited on "a base material in a furnace composed of 3C-SiC polycrystals having at least a surface having a strength ratio of the (111) plane to another crystal plane in powder XRD analysis of 85% or more and 100% or less". It includes not only deposits but also SiC deposits deposited on other in-core substrates.

「粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５%以上、１００%以下である３Ｃ−ＳｉＣ多結晶」において「他の結晶面」は（１１１）面以外の結晶面全てであるが、（２００）面、（２２０）面、（３１１）面が観測されることが多い。
ここで、“３Ｃ−”は立方晶系を意味する。In "3C-SiC polycrystal in which the intensity ratio of the (111) plane to the other crystal plane in the powder XRD analysis is 85% or more and 100% or less", the "other crystal plane" is a crystal plane other than the (111) plane. Although all, the (200) plane, the (220) plane, and the (311) plane are often observed.
Here, "3C-" means a cubic system.

炉内基材の表面の３Ｃ−ＳｉＣ多結晶の損傷の抑制の観点で、粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が９０%以上である方が本発明の効果が発揮されやすく、９５%以上である方がより効果が発揮されやい。 From the viewpoint of suppressing damage to 3C-SiC polycrystals on the surface of the substrate in the furnace, the effect of the present invention is that the strength ratio of the (111) plane to the other crystal planes in the powder XRD analysis is 90% or more. It is easy to exert, and it is easier to exert the effect when it is 95% or more.

本発明によって除去対象となるＳｉＣ堆積物はＳｉＣを主成分として含むものであり、具体的には、化学的気相堆積法（ＣＶＤ法）、有機金属気相成長法（ＭＯＣＶＤ法）、スパッタリング法、ゾルゲル法、蒸着法等の方法を用いて薄膜、厚膜、粉体、ウイスカ等を製造する際に、炉内基材の表面に付随的に堆積した不要なＳｉＣ堆積物が挙げられる。
本発明のクリーニング方法を適用した際に、ＳｉＣ堆積物以外の不要な堆積物が除去されても構わない。The SiC deposit to be removed by the present invention contains SiC as a main component, and specifically, a chemical vapor deposition method (CVD method), a metalorganic vapor phase growth method (MOCVD method), and a sputtering method. , Unnecessary SiC deposits incidentally deposited on the surface of the base material in the furnace when thin films, thick films, powders, whiskers, etc. are produced by using a method such as a sol-gel method or a vapor deposition method.
When the cleaning method of the present invention is applied, unnecessary deposits other than SiC deposits may be removed.

本発明の適用対象となるＳｉＣ堆積物は、粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５％未満の３Ｃ−ＳｉＣ多結晶であり、一例を挙げると、７０％以上〜８５％未満である。他の結晶面は（１１１）面以外の結晶面全てであるが、（２００）面、（２２０）面、（３１１）面が観測されることが多い。 The SiC deposit to which the present invention is applied is a 3C-SiC polycrystal in which the intensity ratio of the (111) plane to the other crystal plane in the powder XRD analysis is less than 85%, for example, 70% or more. ~ 85% or less. The other crystal planes are all crystal planes other than the (111) plane, but the (200) plane, the (220) plane, and the (311) plane are often observed.

上記粉末ＸＲＤ分析の評価方法としては特に限定されないが、例えば装置は、PANalytical製のX’pert Pro MPDを用い、条件はＸ線源としてＣｕＫα、出力 ４５ｋＶ−４０ｍＡで、集中光学系、半導体検出器を使用し、走査域としては２θ：２０〜１００ｄｅｇ、ステップサイズ ０．０１ｄｅｇ、走査速度 ０．１ｄｅｇ／ｍｉｎで実施することができる。それぞれの結晶面の強度は、ピーク高さで評価する。 The evaluation method for the powder XRD analysis is not particularly limited, but for example, the apparatus uses X'pert Pro MPD manufactured by PANalytical, the conditions are CuKα as an X-ray source, an output of 45 kV-40 mA, a centralized optical system, and a semiconductor detector. Can be carried out at a scanning area of 2θ: 20 to 100 deg, a step size of 0.01 deg, and a scanning speed of 0.1 deg / min. The strength of each crystal plane is evaluated by the peak height.

本発明のＳｉＣ単結晶成長炉のクリーニング方法は、不要な堆積物が堆積しやすい製造装置の内壁または半導体ウエハを設置するためのサセプタ、半導体デバイス、コーティング工具などの薄膜を形成する炭化珪素製膜装置やウイスカ、粉末などを製造する炭化珪素製造装置の内壁またはその付属部品に堆積したＳｉＣ堆積物の除去に適用できる。また、炭化珪素の薄膜、厚膜等のみではなく六方晶ＳｉＣウエハなどの大型バルク結晶成長を行う製造装置の内壁またはその付属部品に付着した不要なＳｉＣ堆積物にも適用可能である。これらのうち、成膜装置への適用が好ましく、特に、高温条件での成膜が行われる炭化珪素のエピタキシャル膜成長を行う製膜装置の内壁またはその付属部品に堆積したＳｉＣ堆積物への適用がさらに好ましい。これらの中でも、不要な堆積物が堆積しやすい製造装置の内壁及び半導体ウエハを設置するためのサセプタが特に好適である。 The method for cleaning a SiC single crystal growth furnace of the present invention is a silicon carbide film forming a thin film such as a susceptor, a semiconductor device, or a coating tool for installing an inner wall of a manufacturing apparatus or a semiconductor wafer on which unnecessary deposits are likely to be deposited. It can be applied to the removal of SiC deposits deposited on the inner wall of a silicon carbide manufacturing device for manufacturing devices, whiskers, powders, etc. or its accessories. Further, it can be applied not only to thin films and thick films of silicon carbide, but also to unnecessary SiC deposits attached to the inner wall of a manufacturing apparatus for growing large bulk crystals such as hexagonal SiC wafers or its accessories. Of these, application to a film forming apparatus is preferable, and in particular, application to SiC deposits deposited on the inner wall of a film forming apparatus or its accessories that grow an epitaxial film of silicon carbide that is formed under high temperature conditions. Is even more preferable. Among these, the inner wall of the manufacturing apparatus where unnecessary deposits are likely to be deposited and the susceptor for installing the semiconductor wafer are particularly suitable.

ＳｉＣ単結晶成長炉の内壁に付着するＳｉＣ堆積物と、内壁を構成するＳｉＣ膜（ＳｉＣコート膜）はいずれもＳｉＣ多結晶であることは知られていたが、その明確な違いは明らかではなく、せいぜい表面粗さＲａだけの違いと考えられていた。しかし、その評価方法では、表面粗さが内壁を構成するＳｉＣコート膜と同等なＳｉＣ堆積物を見分けられないことからクリーニング方法を正しく評価できず、実際の装置においては期待通りの効果が得られない、すなわち実際の炭化珪素単結晶成長での結晶欠陥の低減が確認できなかった。
そこで、本発明者らは、ＳｉＣ単結晶成長炉の内壁に付着するＳｉＣ堆積物と内壁を構成するＳｉＣコート膜の構造的な違いを明らかにすべく種々の分析、確認を行ったところ、どちらも同じ３Ｃ−ＳｉＣの多結晶体であるものの、粉末ＸＲＤ分析により定量的に構造を区別でき、その違いは結晶方位面（１１１）配向性の割合に強く現れることを見出した。
内壁を構成するＳｉＣコート膜は３Ｃ−ＳｉＣの多結晶で、その結晶方位面が（１１１）配向性が強く、粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が通常、８５％以上、１００％以下である。ここで他の結晶面は（１１１）面以外のもの全てであるが、（２００）面、（２２０）面、（３１１）面が観測されることが多い。これは結晶面がそろっていることで、その表面反応性は単結晶に近い物性を示すことを意味する。これにより、構造的、化学的安定性を高く保つことができると考えられる。
一方、余分なＳｉＣ堆積物は同じ３Ｃ−ＳｉＣ多結晶であるが、その結晶方位面が無配向に近い。内壁を構成するＳｉＣコート膜における配向性が強い（１１１）面の強度比は８５％未満である。ここで他の結晶面は（１１１）面以外のもの全てであるが、（２００）面、（２２０）面、（３１１）面が観測されることが多い。ＳｉＣ堆積物は内壁を構成するＳｉＣコート膜に対して無配向に近いため、構造的、化学的安定性が劣るものと考えられる。ただし、完全なる無配向ではなく、（１１１）面に配向性がやや認められるのは内壁を構成するＳｉＣコート膜の配向性の影響を受けているためと考えられる。It was known that the SiC deposits adhering to the inner wall of the SiC single crystal growth furnace and the SiC film (SiC coat film) constituting the inner wall are both SiC polycrystals, but the clear difference is not clear. At best, it was thought that the difference was only the surface roughness Ra. However, with that evaluation method, the cleaning method cannot be evaluated correctly because the surface roughness cannot distinguish the SiC deposits equivalent to the SiC coat film constituting the inner wall, and the expected effect can be obtained in an actual device. No, that is, the reduction of crystal defects in the actual growth of silicon carbide single crystal could not be confirmed.
Therefore, the present inventors conducted various analyzes and confirmations in order to clarify the structural difference between the SiC deposit adhering to the inner wall of the SiC single crystal growth furnace and the SiC coat film constituting the inner wall. Although they are the same 3C-SiC polycrystals, the structures can be quantitatively distinguished by powder XRD analysis, and it was found that the difference appears strongly in the ratio of crystal orientation plane (111) orientation.
The SiC coat film constituting the inner wall is a 3C-SiC polycrystal, and its crystal orientation plane is strongly (111) oriented, and the intensity ratio of the (111) plane to other crystal planes in powder XRD analysis is usually 85. % Or more and 100% or less. Here, the other crystal planes are all other than the (111) plane, but the (200) plane, the (220) plane, and the (311) plane are often observed. This means that the crystal planes are aligned and the surface reactivity is close to that of a single crystal. It is considered that this makes it possible to maintain high structural and chemical stability.
On the other hand, the extra SiC deposits are the same 3C-SiC polycrystals, but their crystal orientation planes are close to non-oriented. The strength ratio of the highly oriented (111) plane in the SiC coat film constituting the inner wall is less than 85%. Here, the other crystal planes are all other than the (111) plane, but the (200) plane, the (220) plane, and the (311) plane are often observed. Since the SiC deposit is almost non-oriented with respect to the SiC coat film constituting the inner wall, it is considered that the structural and chemical stability is inferior. However, it is considered that the reason why the (111) plane is slightly oriented rather than completely non-oriented is that it is influenced by the orientation of the SiC coat film constituting the inner wall.

本発明のＳｉＣ単結晶成長炉のクリーニング方法では、炉内基材を構成するＳｉＣコート膜あるいはＳｉＣバルク材と余分なＳｉＣ堆積物とを構造的に区別することで、構造的、化学的安定性の劣る、余分なＳｉＣ堆積物のみを選択的に除去することができる。
特に所定の濃度範囲に希釈されたフッ素ガスを用い、炉内基材をヒーター等で所定の温度範囲に加熱しながら、炉内基材の表面に堆積したＳｉＣを含有する堆積物を効率的に選択的に除去することができる。炉内基材に堆積した不要な堆積物が除去される機構としては、フッ素の熱分解によって生じたフッ素ラジカルが堆積物中のＳｉＣと反応し、ＳｉＦ４、ＣＦ４となることにより除去されると考えられる。
ただし、炉内基材を構成するＳｉＣコート膜あるいはＳｉＣバルク材と、ＳｉＣ堆積物とは結晶方位面の割合は異なるものの、両者とも３Ｃ−ＳｉＣである点では同じであるので、１００％のＦ２ガスを用いた場合には、反応性が強すぎてＳｉＣコート膜、ＳｉＣバルク材およびＳｉＣ堆積物が区別なく除去されてしまうので、最適な選択比とはならない。
そこで、本発明者らは、Ｆ２ガスを不活性ガスで希釈した混合ガスをエッチングガスとして用いたところ、フッ素濃度が１体積％以上、２０体積％以下、好ましくは５体積％以上、１５％以下の範囲で、十分な選択比が得られることを確認した。この濃度範囲に希釈したＦ２ガスを用いることで、緻密な多結晶のＳｉＣ膜あるいはＳｉＣバルク材と、緻密でない多結晶のＳｉＣ堆積物との間のエッチングレートに明確な差を設けることができる。すなわち、エッチングレートの差を利用することで、炉内基材を構成するＳｉＣコート膜あるいはＳｉＣバルク材を実質的にエッチングすることなく、その表面に付着したＳｉＣ堆積物をエッチング除去することができる。In the method for cleaning a SiC single crystal growth furnace of the present invention, structural and chemical stability is achieved by structurally distinguishing the SiC coat film or SiC bulk material constituting the in-furnace substrate from the excess SiC deposits. Only inferior, excess SiC deposits can be selectively removed.
In particular, using fluorine gas diluted to a predetermined concentration range, while heating the furnace base material to a predetermined temperature range with a heater or the like, the SiC-containing deposits deposited on the surface of the furnace base material can be efficiently removed. It can be selectively removed. As a mechanism for removing unnecessary deposits deposited on the base material in the furnace, fluorine radicals generated by thermal decomposition of fluorine react with SiC in the deposits to become SiC 4 and CF 4. it is conceivable that.
However, although the ratio of the crystal orientation planes of the SiC coat film or SiC bulk material constituting the base material in the furnace and the SiC deposit are different, they are the same in that they are both 3C-SiC, so 100% F. When two gases are used, the reactivity is too strong and the SiC coat film, the SiC bulk material and the SiC deposit are removed indiscriminately, so that the optimum selection ratio is not obtained.
Therefore, when the present inventors used a mixed gas obtained by diluting F 2 gas with an inert gas as the etching gas, the fluorine concentration was 1% by volume or more and 20% by volume or less, preferably 5% by volume or more and 15%. It was confirmed that a sufficient selection ratio can be obtained in the following range. By using F 2 gas diluted in this concentration range, it is possible to provide a clear difference in the etching rate between the dense polycrystalline SiC film or SiC bulk material and the non-dense polycrystalline SiC deposit. .. That is, by utilizing the difference in etching rate, it is possible to remove the SiC deposits adhering to the surface by etching without substantially etching the SiC coat film or the SiC bulk material constituting the base material in the furnace. ..

本発明で使用する希釈ガスとしては不活性ガス、空気、または、不活性ガス及び空気を用いることができる。不活性ガスとしては特に限定されるものではないが、窒素ガス（Ｎ２）、アルゴンガス（Ａｒ）、ヘリウムガス（Ｈｅ）が挙げられる。これらの中でも経済性と入手容易性の観点から、Ｎ２、Ａｒが好ましい。不活性ガスは複数種類を用いてもよい。As the diluting gas used in the present invention, an inert gas, air, or an inert gas and air can be used. The inert gas is not particularly limited, and examples thereof include nitrogen gas (N 2 ), argon gas (Ar), and helium gas (He). From the viewpoint of easy availability and even economics of these, N 2, Ar is preferable. A plurality of types of the inert gas may be used.

本発明のクリーニングの際の反応温度（ＳｉＣを含む堆積物が堆積した炉内基材の温度（ＳｉＣ単結晶成長炉内温度））は、２００℃以上、５００℃以下であることが好ましい。この温度範囲であれば、十分なクリーニング性能が得られ、かつ、エッチングレートの差が十分であり、エネルギーの無駄にならず、消費電力などランニングコストも高くならないからである。２５０℃以上、４００℃以下の範囲であることがより好ましく、２５０℃以上、３５０℃以下の範囲であることがさらに好ましい。 The reaction temperature during cleaning of the present invention (the temperature of the substrate in the furnace on which the deposit containing SiC is deposited (the temperature in the SiC single crystal growth furnace)) is preferably 200 ° C. or higher and 500 ° C. or lower. This is because within this temperature range, sufficient cleaning performance can be obtained, the difference in etching rate is sufficient, energy is not wasted, and running costs such as power consumption do not increase. It is more preferably in the range of 250 ° C. or higher and 400 ° C. or lower, and further preferably in the range of 250 ° C. or higher and 350 ° C. or lower.

反応温度は例えば、ＳｉＣ単結晶成長炉の周囲に設置されたヒーターにより制御できる。ヒーターはＳｉＣ単結晶成長炉全体を温める加熱手段を用いてもよいし、加熱ターゲット部材のみを温めてその伝熱により付着物を温めるような加熱手段を用いてもよい。センサーを付着物付近に設置するのが好ましい。センサーを直接ガスに接触させられない場合には、内挿管等を用いてもよい。 The reaction temperature can be controlled, for example, by a heater installed around the SiC single crystal growth furnace. As the heater, a heating means for heating the entire SiC single crystal growth furnace may be used, or a heating means for heating only the heating target member and heating the deposits by the heat transfer may be used. It is preferable to install the sensor near the deposits. If the sensor cannot be brought into direct contact with the gas, an intubation or the like may be used.

本発明のクリーニング時の圧力については、特に制限されるものではない。通常は大気圧下で行うが、例えば、−０．１０ＭＰａＧ以上、０．３ＭＰａＧ以下でも適用可能である。 The cleaning pressure of the present invention is not particularly limited. Normally, it is carried out under atmospheric pressure, but for example, it can be applied to −0.10 MPaG or more and 0.3 MPaG or less.

クリーニングガス（混合ガス）の流量は、特に制限されるものではないが、線速度（ＬＶ）として、０．１ｍ／ｍｉｎ以上、１０ｍ／ｍｉｎ以下が好ましい。 The flow rate of the cleaning gas (mixed gas) is not particularly limited, but the linear velocity (LV) is preferably 0.1 m / min or more and 10 m / min or less.

本発明のクリーニング方法は、ＣＶＤ法により半導体デバイス、コーティング工具などの薄膜を形成する炭化珪素成膜装置やウイスカ、粉末などを製造する炭化珪素製造装置の内壁またはその付属部品に堆積したＳｉＣ堆積物の除去に適用できる。また、炭化珪素の薄膜、厚膜等のみではなく六方晶ＳｉＣウエハなどの大型バルク結晶成長を行う製造装置の内壁またはその付属部品に付着した不要なＳｉＣ堆積物にも適用可能である。これらのうち、成膜装置への適用が好ましく、特に、高温条件での成膜が行われる炭化珪素のエピタキシャル膜成長を行う製膜装置の内壁またはその付属部品に堆積したＳｉＣ堆積物の除去への適用が好ましい。 The cleaning method of the present invention is a SiC deposit deposited on the inner wall of a silicon carbide film forming apparatus for forming a thin film of a semiconductor device, a coating tool, etc., or a silicon carbide manufacturing apparatus for producing whiskers, powder, etc. by a CVD method or its accessories. Can be applied to the removal of. Further, it can be applied not only to thin films and thick films of silicon carbide, but also to unnecessary SiC deposits adhering to the inner wall of a manufacturing apparatus for growing large bulk crystals such as hexagonal SiC wafers or its accessories. Of these, application to a film forming apparatus is preferable, and in particular, for removing SiC deposits deposited on the inner wall of a film forming apparatus or its accessories that grow an epitaxial film of silicon carbide that is formed under high temperature conditions. Is preferred.

以下、実施例により本発明の効果をより明らかなものとする。なお、本発明は、以下の実施例に限定されるものではなく、本発明の効果を発揮し得る範囲で適宜変更して実施することができる。 Hereinafter, the effects of the present invention will be made clearer by examples. The present invention is not limited to the following examples, and can be appropriately modified and implemented as long as the effects of the present invention can be exhibited.

図１に、クリーニング試験で使用した反応炉の断面模式図を示す。
反応炉としては、円筒形の反応管１（ニッケル製）を備えた外熱式縦型反応炉を使用した。円筒形の反応管１には、クリーニングガスを供給するフッ素ガス供給部２と希釈用ガス供給部３が接続されており、反応管１の下流には、ガスを反応管から排出する排気部４が設けられている。さらに、反応管１の外周部には外部ヒーターとして誘導加熱コイル５が設置され、この誘導コイルによって反応管の内部を加熱することができる構成とした。クリーニング試験は、サンプル７（評価用サンプルと対照サンプル）を反応管内部の裁置台６に設置して行った。FIG. 1 shows a schematic cross-sectional view of the reactor used in the cleaning test.
As the reaction furnace, an external heat type vertical reaction furnace equipped with a cylindrical reaction tube 1 (made of nickel) was used. A fluorine gas supply unit 2 for supplying cleaning gas and a dilution gas supply unit 3 are connected to the cylindrical reaction tube 1, and an exhaust unit 4 for discharging gas from the reaction tube is downstream of the reaction tube 1. Is provided. Further, an induction heating coil 5 is installed as an external heater on the outer peripheral portion of the reaction tube 1, and the inside of the reaction tube can be heated by the induction coil. The cleaning test was carried out by placing the sample 7 (evaluation sample and control sample) on the cutting table 6 inside the reaction tube.

（実施例１）
カーボン母材にＳｉＣコートされた炉内基材を有するＳｉＣ単結晶成長炉において、堆積物が堆積していない部分を１ｃｍ角の大きさに切り出し、対照サンプルとした。この炉においてＳｉＣエピタキシャル成長工程を繰り返し行い、ＳｉＣ堆積物が堆積した炉内基材を５ｍｍ角の大きさに切り出し、評価用サンプルとした。(Example 1)
In a SiC single crystal growth furnace having an in-furnace base material coated with SiC on a carbon base material, a portion where no deposits were deposited was cut out to a size of 1 cm square and used as a control sample. The SiC epitaxial growth step was repeated in this furnace, and the in-furnace base material on which the SiC deposits were deposited was cut out to a size of 5 mm square and used as an evaluation sample.

これら２つのサンプルを粉末ＸＲＤ分析により解析した。対照サンプルの正常なＳｉＣコート膜は３Ｃ−ＳｉＣの多結晶で、（１１１）面の強度比は９９%であった。これに対して、評価用サンプルの堆積物面も３Ｃ−ＳｉＣの多結晶であったが（１１１）面の強度比は７６%であった。（１１１）面以外の結晶方位面としては（２００）面、（２２０）面、（３１１）面が観測された。 These two samples were analyzed by powder XRD analysis. The normal SiC coated film of the control sample was a 3C-SiC polycrystalline film, and the intensity ratio of the (111) plane was 99%. On the other hand, the sediment surface of the evaluation sample was also a 3C-SiC polycrystalline, but the intensity ratio of the (111) plane was 76%. As the crystal orientation planes other than the (111) plane, the (200) plane, the (220) plane, and the (311) plane were observed.

粉末ＸＲＤ分析装置はPANalytical製のX’pert Pro MPDを用い、条件はＸ線源としてＣｕＫα、出力 ４５ｋＶ−４０ｍＡで、集中光学系、半導体検出器を使用し、走査域としては２θ：２０〜１００ｄｅｇ、ステップサイズ ０．０１ｄｅｇ、走査速度 ０．１ｄｅｇ／ｍｉｎで実施した。 The powder XRD analyzer uses PANalytical's X'pert Pro MPD, the conditions are CuKα as the X-ray source, the output is 45 kV-40 mA, a centralized optical system and a semiconductor detector are used, and the scanning range is 2θ: 20 to 100 deg. The step size was 0.01 deg and the scanning speed was 0.1 deg / min.

断面をＳＥＭ（Scanning Electron Microscope）観察した結果、図２（Ａ）に示す通り、ＳｉＣコート膜の厚みはいずれも７０μｍ、評価用サンプルのＳｉＣ堆積物（デポ）の厚みはおよそ２５０μｍであった。 As a result of observing the cross section with an SEM (Scanning Electron Microscope), as shown in FIG. 2 (A), the thickness of each SiC coat film was 70 μm, and the thickness of the SiC deposit (depot) of the evaluation sample was about 250 μm.

これら２つのサンプルを、図１に示す内挿管を有するニッケル（Ｎｉ）製の反応管（φ３／４インチ、長さ３０ｍｍ）内の中心位置のサンプル裁置台に設置した。内挿管内のサンプル設置場所付近に熱電対Ｔ１を設置した。 These two samples were placed on a sample arranging table at the center of a nickel (Ni) reaction tube (φ3/4 inch, length 30 mm) having an intubation as shown in FIG. A thermocouple T1 was installed near the sample installation location in the intubation.

反応管を、電気炉を用いて２８０℃に加熱し、大気圧条件下、Ｆ２濃度１０体積％、Ｎ２濃度９０体積％のガスを線速度（ＬＶ）１ｍ／ｍｉｎとなるように流量１８０ｍｌ／ｍｉｎで６０分間流通させた。その結果、図２（Ｂ）に示す通り、ＳｉＣ堆積物層は２１０μｍまで減少したが、ＳｉＣコート膜は７０μｍで変わらなかった。つまり、ここでは測定限界が５μｍなので、ＳｉＣコート膜の減少量は５μｍ未満となる。The reaction tube was heated to 280 ° C. using an electric furnace, under atmospheric conditions, F 2 concentration of 10 vol%, N 2 concentration of 90% by volume of the gas linear velocity (LV) 1m / min to become like flow 180ml It was circulated at / min for 60 minutes. As a result, as shown in FIG. 2 (B), the SiC deposit layer decreased to 210 μm, but the SiC coat film did not change at 70 μm. That is, since the measurement limit is 5 μm here, the amount of reduction of the SiC coat film is less than 5 μm.

エッチングレートは、ＳｉＣ堆積物層については０．６７μｍ／ｍｉｎ、ＳｉＣコート膜については＜０．０８μｍ／ｍｉｎ（５μｍ未満のエッチング量／６０分間）であり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は＞８．４であった。 The etching rate is 0.67 μm / min for the SiC deposit layer and <0.08 μm / min (etching amount less than 5 μm / 60 minutes) for the SiC coat film, and the etching of the SiC deposit layer on the SiC coat film. The rate ratio was> 8.4.

（実施例２）
クリーニングガスの流通時間を３５０分間としたこと以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、図２（Ｃ）に示す通り、ＳｉＣ堆積物層は消失したが、ＳｉＣコート膜の厚みは６５μｍであった。(Example 2)
The cleaning test was carried out under the same conditions as in Example 1 except that the circulation time of the cleaning gas was 350 minutes. As a result, as shown in FIG. 2C, the SiC deposit layer disappeared, but the thickness of the SiC coat film was 65 μm.

エッチングレートは、ＳｉＣ堆積物層については０．７１μｍ／ｍｉｎ以上であり、ＳｉＣコート膜については０．０１４μ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は５１以上であった。 The etching rate was 0.71 μm / min or more for the SiC deposit layer, 0.014 μ / min for the SiC coat film, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 51 or more. ..

（実施例３）
炉内基材に使用したＳｉＣコート膜として、結晶方位面強度が異なるもの、すなわち粉末ＸＲＤ分析による（１１１）面の強度比が９５%のものを使用した。その際のＳｉＣ堆積物層の結晶方位面（１１１）面の強度比は７３％であった。(Example 3)
As the SiC coat film used for the substrate in the furnace, one having a different crystal orientation plane strength, that is, one having a strength ratio of the (111) plane by powder XRD analysis of 95% was used. At that time, the strength ratio of the crystal orientation plane (111) plane of the SiC sediment layer was 73%.

ガスの流通時間を２００分間とした以外は実施例１と同じ条件にてクリーニング試験を行った。なお、断面をＳＥＭ観察した結果、ＳｉＣコート膜の厚みはいずれも７０μｍ、評価用サンプルのＳｉＣ堆積物（デポ）の厚みはおよそ２５０μmであり、実施例１と同じであった。
その結果、ＳｉＣ堆積物層は９５μｍまで減少したが、ＳｉＣコート膜は６６μｍまでの減少に留まった。The cleaning test was carried out under the same conditions as in Example 1 except that the gas circulation time was set to 200 minutes. As a result of SEM observation of the cross section, the thickness of the SiC coat film was 70 μm, and the thickness of the SiC deposit (depot) of the evaluation sample was about 250 μm, which was the same as in Example 1.
As a result, the SiC deposit layer decreased to 95 μm, but the SiC coat film decreased to 66 μm.

エッチングレートは、ＳｉＣ堆積物層については０．７８μｍ／ｍｉｎ、ＳｉＣコート膜については０．０２０μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は３９であった。 The etching rate was 0.78 μm / min for the SiC deposit layer and 0.020 μm / min for the SiC coat film, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 39.

（実施例４）
炉内基材に使用したＳｉＣコート膜として、結晶方位面強度が異なるもの、すなわち粉末ＸＲＤ分析による（１１１）面の強度比が９０%のものを使用した。その際のＳｉＣ堆積物層の結晶方位面（１１１）面の強度比は７０％であった。(Example 4)
As the SiC coat film used for the substrate in the furnace, one having a different crystal orientation plane strength, that is, one having a strength ratio of the (111) plane by powder XRD analysis of 90% was used. At that time, the strength ratio of the crystal orientation plane (111) plane of the SiC sediment layer was 70%.

ガスの流通時間を２００分間とした以外は実施例１と同じ条件にてクリーニング試験を行った。なお、断面をＳＥＭ観察した結果、ＳｉＣコート膜の厚みはいずれも７０μｍ、評価用サンプルの堆積物（デポ）の厚みはおよそ２５０μmであり、実施例１と同じであった。
その結果、ＳｉＣ堆積物層は８０μｍまで減少したが、ＳｉＣコート膜は６５μｍまでの減少に留まった。The cleaning test was carried out under the same conditions as in Example 1 except that the gas circulation time was set to 200 minutes. As a result of SEM observation of the cross section, the thickness of the SiC coat film was 70 μm, and the thickness of the deposit (depot) of the evaluation sample was about 250 μm, which was the same as in Example 1.
As a result, the SiC deposit layer decreased to 80 μm, but the SiC coat film decreased to 65 μm.

エッチングレートは、ＳｉＣ堆積物層については０．８５μｍ／ｍｉｎ、ＳｉＣコート膜については０．０２５μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は３４であった。 The etching rate was 0.85 μm / min for the SiC deposit layer and 0.025 μm / min for the SiC coat film, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 34.

（実施例５）
ガス組成をＦ２濃度５体積％、Ｎ２濃度９５体積％とした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は２２０μｍまで減少したが、ＳｉＣコート膜は７０μｍを保っていた。つまり、ここでは測定限界が５μｍなので、ＳｉＣコート膜の減少量は５μｍ未満となる。(Example 5)
A cleaning test was carried out under the same conditions as in Example 1 except that the gas composition was F 2 concentration 5% by volume and N 2 concentration 95% by volume. As a result, the SiC deposit layer decreased to 220 μm, but the SiC coat film maintained 70 μm. That is, since the measurement limit is 5 μm here, the amount of reduction of the SiC coat film is less than 5 μm.

エッチングレートは、ＳｉＣ堆積物層については０．５０μｍ／ｍｉｎ、ＳｉＣコート膜については＜０．０８μｍ／ｍｉｎ（５μｍ未満のエッチング量／６０分間）であり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は＞６．３であった。 The etching rate is 0.50 μm / min for the SiC deposit layer and <0.08 μm / min (etching amount less than 5 μm / 60 minutes) for the SiC coat film, and the etching of the SiC deposit layer on the SiC coat film. The rate ratio was> 6.3.

（実施例６）
ガス組成をＦ２濃度１５体積％、Ｎ２濃度８５体積％とした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は１９０μｍまで減少したが、ＳｉＣコート膜は６５μｍまでの減少に留まった。
エッチングレートは、ＳｉＣ堆積物層については１．０μｍ／ｍｉｎ、ＳｉＣコート膜については０．０８３μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は１２であった。(Example 6)
A cleaning test was carried out under the same conditions as in Example 1 except that the gas composition was F 2 concentration 15% by volume and N 2 concentration 85% by volume. As a result, the SiC deposit layer decreased to 190 μm, but the SiC coat film decreased to 65 μm.
The etching rate was 1.0 μm / min for the SiC deposit layer and 0.083 μm / min for the SiC coat film, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 12.

（実施例７）
反応管の温度を４００℃にした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は１９０μｍまで減少したが、ＳｉＣコート膜は６５μｍまでの減少に留まった。(Example 7)
The cleaning test was carried out under the same conditions as in Example 1 except that the temperature of the reaction tube was set to 400 ° C. As a result, the SiC deposit layer decreased to 190 μm, but the SiC coat film decreased to 65 μm.

エッチングレートは、ＳｉＣ堆積物層については１．０μｍ／ｍｉｎ、ＳｉＣコート膜については０．０８３μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は１２であった。 The etching rate was 1.0 μm / min for the SiC deposit layer and 0.083 μm / min for the SiC coat film, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 12.

（実施例８）
ガス組成をＦ２濃度１体積％、Ｎ２濃度９９体積％とし、クリーニングガスの流通時間を３５０分間とした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は２１５μｍまで減少したが、ＳｉＣコート膜は７０μｍを保っていた。つまり、ここでは測定限界が５μｍなので、ＳｉＣコート膜の減少量は５μｍ未満となる。
エッチングレートは、ＳｉＣ堆積物層については０．１０μｍ／ｍｉｎ、ＳｉＣコート膜については＜０．０１４μｍ／ｍｉｎ（５μｍ未満のエッチング量／３５０分間）であり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は＞９．３であった。(Example 8)
The cleaning test was carried out under the same conditions as in Example 1 except that the gas composition was F 2 concentration 1% by volume and N 2 concentration 99% by volume, and the circulation time of the cleaning gas was 350 minutes. As a result, the SiC deposit layer decreased to 215 μm, but the SiC coat film maintained 70 μm. That is, since the measurement limit is 5 μm here, the amount of reduction of the SiC coat film is less than 5 μm.
The etching rate is 0.10 μm / min for the SiC deposit layer and <0.014 μm / min (etching amount less than 5 μm / 350 minutes) for the SiC coat film, and the etching of the SiC deposit layer on the SiC coat film. The rate ratio was> 9.3.

（実施例９）
ガス組成をＦ２濃度２０体積％、Ｎ２濃度８０体積％とした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は１３５μｍまで減少したが、ＳｉＣコート膜は６０μｍまでの減少に留まった。
エッチングレートは、ＳｉＣ堆積物層については１．９μｍ／ｍｉｎ、ＳｉＣコート膜については０．１７μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は１１であった。(Example 9)
The gas composition F 2 concentration of 20% by volume, except that the N 2 concentration of 80% by volume were cleaning test under the same conditions as in Example 1. As a result, the SiC deposit layer decreased to 135 μm, but the SiC coat film decreased to 60 μm.
The etching rate was 1.9 μm / min for the SiC deposit layer and 0.17 μm / min for the SiC coat film, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 11.

（比較例１）
炉内基材に使用したＳｉＣコート膜として、結晶方位面強度が異なるもの、すなわち粉末ＸＲＤ分析による（１１１）面の強度比が８０%のものを使用した。その際のＳｉＣ堆積物層の結晶方位面（１１１）面の強度比は５２％であった。(Comparative Example 1)
As the SiC coat film used for the substrate in the furnace, one having a different crystal orientation plane strength, that is, one having a strength ratio of the (111) plane by powder XRD analysis of 80% was used. At that time, the strength ratio of the crystal orientation plane (111) plane of the SiC sediment layer was 52%.

ガスの流通時間を１００分間とした以外は実施例１と同じ条件にてクリーニング試験を行った。なお、断面をＳＥＭ観察した結果、ＳｉＣコート膜の厚みはいずれも７０μｍ、評価用サンプルの堆積物（デポ）の厚みはおよそ２５０μmであり、実施例１と同じであった。
その結果、堆積物層は７０μｍまで減少し、ＳｉＣコート膜も１０μｍまで減少した。The cleaning test was carried out under the same conditions as in Example 1 except that the gas circulation time was set to 100 minutes. As a result of SEM observation of the cross section, the thickness of the SiC coat film was 70 μm, and the thickness of the deposit (depot) of the evaluation sample was about 250 μm, which was the same as in Example 1.
As a result, the sediment layer was reduced to 70 μm, and the SiC coat film was also reduced to 10 μm.

エッチングレートは、ＳｉＣ堆積物層については１．８μｍ／ｍｉｎ、コート層については０．６０μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は３．０であった。 The etching rate was 1.8 μm / min for the SiC deposit layer and 0.60 μm / min for the coat layer, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 3.0.

（比較例２）
炉内基材に使用したＳｉＣコート膜として、結晶方位面強度が異なるもの、すなわち粉末ＸＲＤ分析による（１１１）面の強度比が７０%のものを使用した。その際のＳｉＣ堆積物層の結晶方位面（１１１）面の強度比は３８％であった。(Comparative Example 2)
As the SiC coat film used for the substrate in the furnace, one having a different crystal orientation plane strength, that is, one having a strength ratio of the (111) plane by powder XRD analysis of 70% was used. At that time, the strength ratio of the crystal orientation plane (111) plane of the SiC sediment layer was 38%.

ガスの流通時間を１００分間とした以外は実施例１と同じ条件にてクリーニング試験を行った。なお、断面をＳＥＭ観察した結果、ＳｉＣコート膜の厚みはいずれも７０μｍ、評価用サンプルの堆積物（デポ）の厚みはおよそ２５０μmであり、実施例１と同じであった。
その結果、ＳｉＣ堆積物層は６０μｍまで減少し、ＳｉＣコート膜はわずかに残存が確認できるのみでほぼ消滅した。
エッチングレートは、ＳｉＣ堆積物層については１．９μｍ／ｍｉｎ、ＳｉＣコート膜については０．７０μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は２．７であった。The cleaning test was carried out under the same conditions as in Example 1 except that the gas circulation time was set to 100 minutes. As a result of SEM observation of the cross section, the thickness of the SiC coat film was 70 μm, and the thickness of the deposit (depot) of the evaluation sample was about 250 μm, which was the same as in Example 1.
As a result, the SiC deposit layer decreased to 60 μm, and the SiC coat film almost disappeared with only a slight residual confirmation.
The etching rate was 1.9 μm / min for the SiC deposit layer and 0.70 μm / min for the SiC coat film, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 2.7.

（比較例３）
反応管の温度を５５０℃にした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は２００μｍまで減少し、ＳｉＣコート膜も５０μｍまで減少した。
エッチングレートは、ＳｉＣ堆積物層については０．８３／ｍｉｎ、コート層については０．１７μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は４．９であった。(Comparative Example 3)
The cleaning test was carried out under the same conditions as in Example 1 except that the temperature of the reaction tube was set to 550 ° C. As a result, the SiC deposit layer was reduced to 200 μm, and the SiC coat film was also reduced to 50 μm.
The etching rate was 0.83 / min for the SiC deposit layer and 0.17 μm / min for the coat layer, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 4.9.

（比較例４）
反応管の温度を１５０℃にした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は２５０μｍのまま変化せず、ＳｉＣコート膜も７０μｍのまま変化しなかった。(Comparative Example 4)
The cleaning test was carried out under the same conditions as in Example 1 except that the temperature of the reaction tube was set to 150 ° C. As a result, the SiC deposit layer remained unchanged at 250 μm, and the SiC coat film remained unchanged at 70 μm.

（比較例５）
ガス組成をＦ２濃度３０体積％、Ｎ２濃度７０体積％とした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は２１０μｍまで減少し、ＳｉＣコート膜も５０μｍまで減少した。
エッチングレートは、ＳｉＣ堆積物層については０．６７μｍ／ｍｉｎＳｉＣコート膜については０．１７μｍ／ｍｉｎであり、ＳｉＣコート膜に対するＳｉＣ堆積物層のエッチングレート比は３．９であった。(Comparative Example 5)
A cleaning test was carried out under the same conditions as in Example 1 except that the gas composition had an F 2 concentration of 30% by volume and an N 2 concentration of 70% by volume. As a result, the SiC deposit layer was reduced to 210 μm, and the SiC coat film was also reduced to 50 μm.
The etching rate was 0.67 μm / min for the SiC deposit layer and 0.17 μm / min for the SiC coat film, and the etching rate ratio of the SiC deposit layer to the SiC coat film was 3.9.

（比較例６）
ガス組成をＦ２濃度体積０．５％、Ｎ２濃度９９．５体積％とした以外は実施例１と同じ条件にてクリーニング試験を行った。その結果、ＳｉＣ堆積物層は２５０μｍのまま変化せず、ＳｉＣコート膜も７０μｍのまま変化しなかった。(Comparative Example 6)
A cleaning test was carried out under the same conditions as in Example 1 except that the gas composition was F 2 concentration volume 0.5% and N 2 concentration 99.5 volume%. As a result, the SiC deposit layer remained unchanged at 250 μm, and the SiC coat film remained unchanged at 70 μm.

実施例及び比較例の結果を表１にまとめて示す。 The results of Examples and Comparative Examples are summarized in Table 1.

Figure 0006964520
Figure 0006964520

実施例１と比較例４とを比較すると、実施例１と同じフッ素ガス濃度および反応時間でも、反応温度が１５０℃ではＳｉＣ堆積物をエッチングすることができないことがわかった。また、実施例１と比較例３とを比較すると、実施例１と同じフッ素ガス濃度および反応時でも、反応温度が５５０℃ではエッチングレート比は十分に得られないことがわかった。
実施例１と比較例６とを比較すると、実施例１と同じ反応温度および反応時間でも、フッ素ガス濃度が０．５体積％ではＳｉＣ堆積物をエッチングすることができないことがわかった。また、実施例１と比較例５とを比較すると、実施例１と同じ反応温度および反応時でも、フッ素ガス濃度が３０体積％ではエッチングレート比は十分に得られないことがわかった。
実施例１と比較例１および比較例２とを比較すると、炉内基材の表面を構成する３Ｃ−ＳｉＣ多結晶の粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５％未満では、十分なエッチングレート比が得られないことがわかった。Comparing Example 1 and Comparative Example 4, it was found that the SiC deposit could not be etched at a reaction temperature of 150 ° C. even at the same fluorine gas concentration and reaction time as in Example 1. Further, when Example 1 and Comparative Example 3 were compared, it was found that the etching rate ratio could not be sufficiently obtained when the reaction temperature was 550 ° C. even at the same fluorine gas concentration and reaction as in Example 1.
Comparing Example 1 and Comparative Example 6, it was found that the SiC deposit could not be etched at a fluorine gas concentration of 0.5% by volume even at the same reaction temperature and reaction time as in Example 1. Further, when Example 1 and Comparative Example 5 were compared, it was found that the etching rate ratio could not be sufficiently obtained when the fluorine gas concentration was 30% by volume even at the same reaction temperature and reaction time as in Example 1.
Comparing Example 1 with Comparative Example 1 and Comparative Example 2, the intensity ratio of the (111) plane to the other crystal planes in the powder XRD analysis of the 3C-SiC polycrystals constituting the surface of the substrate in the furnace was 85. It was found that a sufficient etching rate ratio could not be obtained when the ratio was less than%.

１ 反応管
２ フッ素ガス供給部
３ 希釈用ガス供給部
４ 排気部
５ 誘導加熱コイル
６ サンプル裁置台
７ サンプル1 Reaction tube 2 Fluorine gas supply unit 3 Dilution gas supply unit 4 Exhaust unit 5 Induction heating coil 6 Sample cutting table 7 Sample

Claims (4)

少なくとも表面が粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５%以上、１００%以下である３Ｃ−ＳｉＣ多結晶からなる炉内基材を備えたＳｉＣ単結晶成長炉を、ガスを用いてクリーニングする方法であって、
フッ素ガスと不活性ガスとの混合ガスを、ノンプラズマ状態で前記ＳｉＣ単結晶成長炉内に流通させて、該ＳｉＣ単結晶成長炉内に堆積したＳｉＣ堆積物を選択的に除去するものであり、
前記ＳｉＣ堆積物は、粉末ＸＲＤ分析での他の結晶面に対する（１１１）面の強度比が８５％未満の３Ｃ−ＳｉＣ多結晶であり、
前記混合ガスは１体積％以上、２０体積％以下のフッ素ガスと８０体積％以上、９９体積％以下の不活性ガスとからなり、ＳｉＣ単結晶成長炉内温度が２００℃以上、５００℃以下であることを特徴とするＳｉＣ単結晶成長炉のクリーニング方法。 A SiC single crystal growth furnace having an in-core substrate composed of 3C-SiC polycrystalline having at least a surface having a strength ratio of the (111) plane to another crystal plane of 85% or more and 100% or less in powder XRD analysis. , A method of cleaning with gas,
A mixed gas of fluorine gas and an inert gas, were then circulated to the SiC single crystal growth furnace in a non-plasma state, intended to selectively remove the SiC deposits deposited on the SiC single crystal growth furnace can be,
The SiC deposit is a 3C-SiC polycrystal having a (111) plane intensity ratio of less than 85% to other crystal planes in powder XRD analysis.
The mixed gas is composed of 1% by volume or more and 20% by volume or less of fluorine gas and 80% by volume or more and 99% by volume or less of an inert gas, and the temperature in the SiC single crystal growth furnace is 200 ° C. or more and 500 ° C. or less. A method for cleaning a SiC single crystal growth furnace, which is characterized by being present. 前記不活性ガスが、窒素ガス、アルゴンガス、及びヘリウムガスからなる群から選択されたものであることを特徴とする請求項１に記載のＳｉＣ単結晶成長炉のクリーニング方法。 The method for cleaning a SiC single crystal growth furnace according to claim 1, wherein the inert gas is selected from the group consisting of nitrogen gas, argon gas, and helium gas. 前記不活性ガスが窒素ガスまたはアルゴンガスのいずれかであることを特徴とする請求項２に記載のＳｉＣ単結晶成長炉のクリーニング方法。 The method for cleaning a SiC single crystal growth furnace according to claim 2, wherein the inert gas is either nitrogen gas or argon gas. 前記ＳｉＣ単結晶成長炉は、ＳｉＣインゴット製造装置が備える炉である、請求項１〜３のいずれか一項に記載のＳｉＣ単結晶成長炉のクリーニング方法。 The method for cleaning a SiC single crystal growth furnace according to any one of claims 1 to 3, wherein the SiC single crystal growth furnace is a furnace included in a SiC ingot manufacturing apparatus.
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